How is this defined?
Do you consider yourself an expert at something?
If so, what is the unit of measurement? Years, Projects, Trophies, Scars, Wrinkles, Grey Hairs?
Does the audience that you’re displaying your capabilities to/for consider you as an expert?
Maybe the audience today believes you to be an expert, but if you were to deliver the same level of skills to a different audience tomorrow, they may not, as they’re, in fact, the experts…
Unfortunately though, if you’re not an expert, what are you?
An amateur? Ouch!
Let’s stick with Expert, as it sounds much more profound.